This application is directed to a tool handle having an inner shell with a molded overlay wherein the overlay includes at least two side by side sections having different characteristics and a method of manufacture thereof such that the sections blend together smoothly and do not include molding gate marks.
Construction workers require tools that are durable and will withstand significant daily use over long periods of time. Preferably, such tools are also comfortable in the hand of the user and provide the user with a good grip. Handles are, therefore, often constructed with an inner shell that provides form and shape to the handle and then soft pliable overlay that provides a comfortable surface to the user.
Such handles also represent a substantial amount of weight in many tools such as trowels and floats. Consequently, it is desirable to reduce the weight as much as possible. For this reason, portions of such handle where the handle attaches to a tool may be hollow, whereas the portion of the handle that is to be grasped by the user may include more internal structure or be solid in order to prevent collapse due to pressure exerted by the craftsman during use.
Because such handles must be designed to comfortably fit the grip of the user, provide structure to attach to a tool, have certain portions that are hollow to reduce weight and for other reasons, the overall handle is typically a complex geometric structure which can present problems in molding, but the outer surface can be molded by most modern molding techniques when just a uniform over-mold or cover is applied to a shell.
However, it is sometimes also desirable to have an over-mold that has sections with different characteristics. For example, it may be desirable to have sections or inlays with different degrees of softness or resiliency to the remainder of the overlay so as to improve the gripping characteristics in certain areas or, more commonly, it may be desirable to have sections with significantly different colors for purposes of either design or providing information to the user.
In some instances it is possible to provide a base over-mold and then apply very superficially or just on the surface of the over-mold very thin layers of material that incorporates the second characteristic. In commercial hand tools, this does not work very well, since the tools are used for a long time and the superficial regions wear away fairly rapidly. Consequently, it is preferably that the two different characteristics be provided by sections of the over-mold that have approximately the same depth and, therefore, are likely to not wear out at different times. It is possible to apply to a shell a first overlay that covers a portion of the shell and has a first characteristic and then apply a second overlay that has the second characteristic by using a separate second exterior mold to produce letters, geometric designs or the like. However, when conventional molding techniques are used to apply inlays or the second section in and about the first section of the overlay, blemishes are created due to normal gating and parting lines that are highly undesirable. That is, at the end of the molding process, the molding material that is supplied to those sections through the mold must be somehow separated from the channels in the mold that are supplying the material. When the channels supply the molding material from the exterior of the exterior of the device gate marks and parting lines occur. Therefore, it is desirable to provide a molding method or technique that produces a final handle that includes an outer grippable portion that has an overlay that is comfortable to the user and that has separate external sections of an overlay that have different characteristics such as color and which are substantially free from blemishes that would be caused by molding the second portions of the outer mold by use of conventional molding techniques.
A handle for use in conjunction with commercial tools and the like includes a central carrier or shell for providing shape and strength to the handle. The shell has an exterior surface and a series of internal ribs in a gripping portion of the handle. The shell also includes at least one attachment portion for joining the shell to the tool.
The shell is initially placed in a first mold wherein a first over-mold is placed on the shell. The shell includes at least one internal channel running therethrough that communicates with the surface. The first mold allows for injection of a soft molding material onto the surface of the shell except in certain regions that are blocked by the mold. The blocked regions communicate with the internal channel shell and the mold is designed to cooperatively blocked flow of material through the channel and flow into the block regions during the first molding procedure.
After removal of the shell from the first mold, it has a first section of an over-mold thereon that covers a substantial portion of the surface and has adjacent regions that include no over-mold and which are joined to the shell channel. The channel also joins with an underside of the handle grip portion.
The handle with the first over-mold thereon is then placed in a second mold. The second mold allows for flow of a second molding material into the regions that were blocked by the first mold. The second material flows from the underside of the handle, through the channel and into the second over-mold open regions to produce second over-mold sections having different characteristics than the first over-mold sections. Often the second over-mold sections are inlays of the first over-mold section or completely surrounded by the first over-mold section. Subsequently, the second mold is removed. The first over-mold and the second over-mold are adjacent to one another and form a smooth transition therebetween without blemishes caused by gating or parting lines except on the underside of the handle where such blemishes are not visible.
The fastening section or sections preferably are hollow and have cavities so as to reduce weight of the handle. In order to seal about the cavities of the fastening sections, the over-mold is extended slightly beyond the shell whereat the handle abuts with the tool. In this manner, as the tool is secured to the handle by a fastener, pressure exerted compresses the over-mold extension and produces a seal between the tool and the hollow cavity of the fastening section. Likewise, where a fastener such as a bolt, rivet or the like is utilized for securing the handle to a tool, a receptacle is provided for the fastener and an upper bead is provided about the receptacle that is compressed by the fastener and produces a sealing therebetween. This allows the cavity to remain watertight when the tool is used in liquids or cleaned.
Therefore, the objects of the present invention are: to provide a handle for use in conjunction with tools, especially commercial tools, that is comfortable, resilient and easy to grip by the user while providing a strong internal structure; to provide such a handle having a molded overlay that has at least two adjacent sections having different characteristics such as different colors; to provide such a handle constructed from a shell having at least one interior channel that allows flow of moldable material through the interior of the handle to a second overlay region or section subsequent to the application of a first overlay region or section on the surface of the handle; to provide such a handle including at least one gripping portion and one fastening portion adjacent to the gripping portion and wherein the fastening portion is hollow for reduction of weight; to provide such a handle wherein the fastening portion includes an extension of the over-mold beyond the shell in the region whereat the fastening section mates with the remainder of a tool to which it is to be secured, so that the extension compresses during joining of the handle to the remainder of the tool to seal an internal cavity against seepage or water; to provide a method of producing such a handle wherein a shell is provided and placed in a first mold and a first molding material to produce a first over-mold is applied to the shell in the first mold that covers a substantial portion of the exterior of the shell, thereafter the shell with the first over-mold thereon is placed in a second mold and a second molding material to produce a second over-mold or inlay and is placed on the shell into second molding regions in a second molding process, so as to cover regions of the shell exterior not covered by the first over-mold; to provide such a molding process wherein a channel is provided within the interior of the shell and the first mold blocks both the channel and the second molding regions from application of the first molding material during the first molding process; to provide such a molding process wherein the second molding material is applied through the channel to the second molding regions from an underside of the handle to prevent parting lines and gating blemishes on the visible surface of the gripping portion of the handle; to provide such a molding process that allows for application of the first molding material and the second molding material in adjacent regions with a smooth transition therebetween and, preferably, with a substantially uniform thickness therebetween so as to provide a clean, long lasting combined over-mold; to provide such a method that allows for application of separate regions to the surface of the handle that are of substantially different characteristics, such as hardness or color; and to provide such a handle which is comparatively inexpensive to produce, very usable in service and especially well adapted for the intended usage thereof.
Other objects and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention.
The drawings constitute a part of this specification and include exemplary embodiments of the present invention and illustrate various objects and features thereof.